what colors are you using? If I'm following RobA's artistic regional map tutorial and using the colors there I might use one of the darker dirt colors as low and #dddddd as high, then apply a mask to it. I might also use the same dirt color above that (masked to the mountain shape again) and set the layer to 'soft light' mode. You can see the results at http://www.kjd-imc.org/2010/10/22/va...-reinterpeted/ (yeah, I kind of pooched blending the edges of the mountains, but I can live with it)